1. Field of the Invention
The present invention relates to a method of forming a laminated core for forming a magnetic path and an electromagnetic type valve driving device to which the laminated core for forming a magnetic path is applied.
2. Description of the Prior Art
A laminated core part used for an electromagnetic type valve driving device generates a magnetic field by an electric current to drive a movable iron core, thereby opening/closing a valve fixed to a valve shaft via a coupling shaft integrally formed with the movable iron core. In this case, since a considerably large force is necessary for driving the valve, the laminated core part needs to be strengthened strong and to be joined to the movable iron core with high accuracy. Otherwise, the laminated core part itself is attracted by an electromagnetic attractive force, which causes distortion or breakage. Thus, conventionally, the laminated core part is fixed by a projection formed at the shoulder portion thereof or by another member inserted into a through hole made in the laminated core part.
Since the laminated core part is formed in the manner described above, it can be easily fixed but has the following drawbacks: in the former method, fixing only the shoulder portion causes a strain at the center portion and utilizing the shoulder portion enlarges the size thereof in the lateral direction, which may be preferably avoided since the lateral direction is a direction where the valves are adjacent to each other; in the latter method, if the inserted member is not enough large in size, the laminated core, together with the inserted member, is distorted by the electromagnetic attractive force. Further, the latter method is thought to present a problem that a large through hole reduces power because the through hole is made in the laminated core itself. Still further, the latter method raises a problem that because a considerably large force is applied to the laminated core part, the laminated core part can not be divided and that another member provided with a winding is inserted into the laminated core part, which results in the inefficient use of the space of the winding.
The present invention has been made to solve the above drawbacks. The object of the present invention is to provide a method of forming a laminated core part by which the laminated core part can be assembled with enhanced ease and accuracy and be increased in mechanical strength, and an electromagnetic type valve driving device using the laminated core part as an iron core for forming a magnetic path.
According to a first aspect of the present invention, there is provided a method of forming a laminated core, comprising the steps of: forming a center core laminated part and a side core laminated part separately; and integrating the center core laminated part with the side core laminated part by engaging depressed engaging portions with projected engaging portions, wherein the depressed engaging portions and the projected engaging portions are formed relatively on the corresponding opposite surfaces in the shape of an inverted wedge, to form a laminated core part for forming a magnetic path.
Here, the forming step may include a step of forming a top base and a bottom base separately, and the integrating step may include a step of engaging depressed engaging portions with projected engaging portions which are formed relatively on the corresponding opposite surfaces in the shape of an inverted wedge.
Then, an inwardly bent portion may be formed at the end portion of the side core laminated part and a depressed engaging portion formed on the inwardly bent portion may be engaged with a projected engaging portion, which is formed relatively on the opposite surface of the center core laminated part, the top base or the bottom base opposite to the inwardly bent portion in the shape of an inverted wedge, to integrate the side core laminated part with the center core laminated part, the top base or the bottom base.
In addition, depressed engaging portions may be formed relatively on the corresponding opposite surfaces of the center core laminated part, the side core laminated part, the top base and the bottom base in the shape of an inverted wedge, and wherein separate engaging members, each of which has projected engaging portions formed on both surfaces thereof in the shape of an inverted wedge, may be engaged with the depressed engaging portions opposed thereto to integrate the center core laminated part, the side core laminated part, the top base and the bottom base into one piece.
According to a second aspect of the present invention, there is provided an electromagnetic type valve driving device comprising: an iron core for forming a magnetic path; a movable iron core forming a part of the iron core for forming a magnetic path; a coil for generating a magnetic flux when an electric current is passed therethrough; a movable iron core coupling shaft coupled with the movable iron core at the end portion thereof and driven by an electromagnetic force and a spring force; and a valve shaft made to abut on the end surface of the movable iron core coupling shaft by the spring force, characterized in that a center core laminated part and a side core laminated part, which are formed separately from each other, are integrated with each other by engaging depressed engaging portions with projected engaging portions, wherein the depressed engaging portions and the projected engaging portions are formed relatively on the corresponding opposite surfaces in the shape of an inverted wedge, to form the iron core for forming a magnetic path.
Here, the electromagnetic type valve driving device may further comprise: a top base and a bottom base, which are formed separately from each other, are integrated into one piece by engaging depressed engaging portions with projected engaging portions, wherein the depressed engaging portions and the projected engaging portions are formed relatively on the corresponding opposite surfaces in the shape of an inverted wedge.